Melting furnace



June 18, 1929. w. s F 1,717,813

"mm FpRnAcE Filed March 15, 1928 QMM I Z7 Ma,

Patented June l8, 1929.

UNITED STA ES.

PATENT OFFICE.

WILHELM STEFFE, OF NEUNKIRCHEN, GERMANY, ASSIGNOR TO FREIER GRUNDER EISEN- UND METALLWEBKE GESELLSCHAFT MIT BESCHRANKTER HAI'L'UNG, OF

NEUNKIBCHEN, GERMANY, A COMPANY OF GERMANY.

MELTIN G FURNACE.

Application filed Marchl15, 1928, Serial No. 262,019, and in Germany July 21, 1927.

My inventionrelates to melting furnaces and especially to cupola furnaces, in front of which is arranged a front hearth or re ceiver intended to receive the molten metal and removed some distance from the furnace shaft. The object of the.invention is to provide in such furnaces a simple and easily operated arrangement for continuously discharging the molten metal when the furnace is in blast, so that it is immediately withdrawn from the action of the blast and is separated from the slag. This arrangement is such moreover that the residue of the molten metal left in .the furnace at the end of the operation can also be easily withgrzitwnthrough a readily accessible tapping A still further object of the invention is to force the metal and the slag through a single opening situated at the level of the fur nace hearth into an open slag separator from which it can be continuously discharged at two different liquid levels; a hot and therefore fluid slag bein obtained owin to the slag being drawn rom the lower ayer of the slag bath in the furnace shaft which is situated directly above the metal bath.

As after the column of slag in the furnace reaches a certain depth all the freshly melted slag or metal escapes immediately, the liquid level in the furnace will remain constant from that moment. The position of the melting zone situated above the liquid level will not therefore change which is an important point for obtaining a. uniformly hot iron.

The oxides of the metal produced in the melting zone are reduced again in the slag column the depth of whichshould be at least 500 mm. and which is maintained constantly at the same level. This reduces waste. The slag esca ing from the slag separator is practically ree from iron and the iron discharged from the slag separator is free from slag. Owing to the purity of the iron faulty castings are avoided and desulphurizing or other refinement of the iron in the receiver is rendered possible or assisted as if there is acid furnace slag present iron cannot be desulphurized or refined. As the surface ofthe bath in the slag separator is not exposed to the pressure of the blast, any gases occluded in the metal can easily separate and this assists the production of a casting free from pores. Moreover as the melted metal leaves the furnace shaft at once it is possible without any difliculty to separate difi'erent alloys in onemelt and owing to the continuous discharge of the molten metal the danger which is caused in other furnaces by the intermittent tapping of the,

metal is avoided.

Other advantages of the invention will be clear to the expert from the following description.

The accompanying drawing shows, by

way of example of a construction according ping hole y which is thus connected to the opening is. The tapping hole 3 can be closed in the usual manner. C ose to the upper edge of the slag separator chamber t is provided an outlet 9 through which the slag is discharged; lower down is provided an outlet h which rises obliquely upwards from the chamber 2? and leads into a trough f. The

end of the trough f extends over the receiver 0. In passing through the rising portion of the chamber t, the cast iron and the slag are superposed; the slag constantly flows from the layer a situated directly above the iron on the furnace hearth and there is a simultaneous continuous flow of the iron. After the two masses of liquid have been separated in the chamber 6 the slag escapes through the upper outlet 9, and the iron flows through the obliquely rising conduit it from the point near the bottom of the separationchamber, that is to say from a layer free from slag. The slag is at the same time so hot and fluid that it can be used to cast castings with sharp edges, whereas the slag which is usually drawn from the upper slag layer I) constantly cooled by the blast is not so hot or fluid.

The level of the outlet g and the height of the highest point of the rising outlet 71. above the opening is control the depth of the liquid metal and of the slag in the slag separator,

and therefore the pressure which the liquid exerts in the slag separator on the contents of the furnace. These levels are calculated in such a manner that the sum of the pressures of the liquid metal and of the slag in the slagseparator is only very slightly greater than the sum of the pressures of the.blast and of chamber.

When the melting is finished, the tapping hole y is opened. The remainder of the metal escapes through this tapping hole from the furnace shaft and. from the separation chamber. As soon as the slag appears, the hole is closed. The slag still remaining in the furnace shaft and in the conduits is drained off through the bottom valve of the furnace.

I claim: Y C A cupola furnace comprising a-shaft and a hearth provided with an outlet at its lowest point in combination with a slag separatorchamber-having an inclined roof and provided with" two outlets, one of said outlet being near the upper edge of the wall of said chamber and disposed above the second outlet, and also a tapping hole arranged approximately at the level ofthe hearth and connected to the'aforesaid outlet therefrom at its lowest point in a straight line.

In testimony whereof I have aflixed 'my signature.

WILHELM STEFFE. 

